"Will the crew include a doctor?" "The very best, so far as technical skill goes. But circ.u.mstances might arise where more than technical skill would be needed, so that's why we have the auxiliary control station."

General Gordon tentatively touched a red k.n.o.b on the observer's panel. "Does this turn the disintegrators on?" he asked.

Knight nodded. "It turns them on, and also controls the maximum range. The Computer gave us that safety gadget I spoke of when you were here a year ago, so now we don't have to worry about them being turned on accidentally and destroying the ship."

He spun the red k.n.o.b to the right and the generals exchanged nervous glances. "It's on full intensity, right now. This safety gadget prevents the closing of the circuit so long as the ship is within an atmosphere dense enough to produce a feedback of the rays."

He turned it off again and General Marker remarked, "You certainly go all the way in trusting your gadgets here."

"A soundly built gadget can be trusted."

"Then why your five-word slogan-the same as you have on the Master Computer- in big letters here on the observer's panel?"

"It's different when a gadget has an intelligence. The observer, in an emergency, would have to control the ship through a robotic brain. That five-word sentence, which is actually a sound philosophy to keep in mind when dealing with machines, is to remind the observer that he is not giving orders to a human pilot."

"Although it's six hours until take-off, I suppose the ship is ready to go right now?"

General Gordon asked.

"Ready to go, and Miles and Vickson are now getting their last hours of sleep-the last hour, to be exact. They'll be back down here in less than two hours, together with myself, Dr. Clarke, and about a platoon of technicians to make the last-minute check of all the other checking. We have something too big in s.p.a.ce flight to chance any errors on the first attempt."

"I'm glad this ship's first flight will not be as a weapon of war," General Marker said, "but I trust it's well guarded-just to play safe, as you said of your ground-control station."

"You saw the guards outside," Knight answered. "And there are guards outside the door of the ground-control station-this ship can't lift while enclosed in this steel building and the controls that lower the roof and walls into recesses in the ground are inside that station. We still have the machine-gun towers that we erected seven years ago when war seemed just around the corner. The antiaircraft artillery is still stationed in a wide circle around Computer Center-no one ever got around to ordering their removal and the guns were still manned twenty-four hours a day, the last I heard."

"Well, if Russo-Asia has any plans for this ship, they've certainly kept them well concealed," General Marker said. "Our Intelligence reports no indications whatever of any such thing. And now, I think we had all better get out of here and take advantage of that less-than-two-hours sleep we'll get before the preliminaries start."

Knight noticed, as they went down out of the ship, that George was still in the drive room, checking the control panel to drive circuits. The robot did not look up from its work, though it saw them pa.s.s. Robots confined their speaking to necessary answers and wasted no time with such amenities as "Good morning" and "Good night."

He parted company with the two generals at the Computer area gate; they to return to their Center hotel and he to drive through the slumbering streets to his own cottage. Tired and sleepy, he set the alarm to arouse him in an hour and a half and went to bed.

He had been asleep an hour and fifteen minutes when he was awakened by the ringing of the doorbell and June's voice. "Blacky-wake up!"

"What is it?" he called, swinging his feet to the floor and reaching for his clothes.

"Come over to Tim's house." There was both indignation and urgency in June's tone.

"See if you can straighten things out."

He heard her hurry back to the Miles' cottage, her footsteps clicking sharp and fast on the walk. He grinned, despite his worry that Tim might be in some kind of trouble-the manner of her walking indicated that June was beginning to get mad.

He put on his clothes and went out into the pre-dawn darkness. The lights were on in the Miles' cottage and there was a black sedan parked at the curb before it. It had a government-service license plate, but there was nothing about the number on the plate to indicate the type of service it represented.

Tim Miles' voice came from within the house, angry and incredulous, and a vaguely familiar voice answered him. Knight went to the door and entered without knocking.

There were four in the room; Tim Miles, Connie, June, and a cold-eyed man in a gray suit. Knight recognized him with a start; his name was Whitney and he was a Security man. He returned Knight's "h.e.l.lo" with a nod of recognition and Connie, sitting in a chair by the card table, said, "h.e.l.lo, Blacky." Miles, red-faced and scowling, hardly glanced away from Whitney, while June sat one-hipped on the card table beside Connie, her eyes smoldering and her hands gripping the edge of the table until the knuckles were white.

Knight stopped beside Whitney. "What is this?" he asked.

"The ship has been sabotaged," Whitney replied.

"It's a lie!" Miles declared.

"Just a minute-" Knight looked from Miles back to Whitney. "It wasn't sabotaged when I left it an hour ago."

"It was sabotaged a year ago," Whitney said. "We didn't learn of it until tonight-in fact, not over half an hour ago."

"Are you sure?" Knight asked.

"I'm supposed to have done it!" Miles burst out wrathfully. "I'm supposed to have cross-wired the circuits from the control panel to the drive so that the drive will explode on take-off."

Knight made his reply to Whitney. "I can't believe that. I've known Miles and worked with him for several years. Of course, I realize that Security wants more positive proof of a suspected man's innocence than the personal opinion of his friends. If you will give me the details, perhaps I can help."

"He isn't exactly accused, yet," Whitney said, "but he's very much under suspicion of performing the work of sabotage. As for the reasons for our suspicions, they are these: "The robot, George, has been helping Miles and Vickson check the ship today; an extra safety measure, I understand, to make sure there will be no mechanical failures on the ship's trial flight tomorrow. Miles completed his share of the work early in the afternoon and went home. Vickson was through about an hour later and he went home, leaving the robot to check the control-panel-to-drive circuits-a precautionary measure that Miles, here, admits he insisted was not necessary. It was about thirty minutes ago that the robot finished checking the circuits. He then phoned Security-a thing he had been ordered to do if he ever found any evidence of sabotage-and informed us that the drive circuits had been so cross-circuited that the drive would explode the moment it was activated for take-off."

Miles sighed heavily. "I tell you, those circuits are not sabotaged! I installed them myself, and I personally welded the control panel seals."

"You say this sabotage was supposed to have been done a year ago?" Knight asked.

"That's right," Whitney said. "Miles admits that he, himself, installed the circuits and sealed the panel at that time-and the panel is still sealed."

"Yes, I admit it!" Miles snapped. "Those circuits are not cross-wired. I don't know what this is all about, but I do know the kind of job I did on those circuits."

"The robot traced the circuits and found them to be cross-wired," Whitney said. "Isn't it true that a robot never lies?"

A look of helplessness pa.s.sed over Miles' face. "Yes, it's true-but there's some mistake."

Whitney turned his cold eyes on Connie who was sitting quietly in her chair, watching Whitney with a composure that was in such striking contrast to the ever- growing wrath of the hot-eyed June.

"There's something else-" he said, and June froze into a waiting tenseness. "Why do you so often go to the park at Saguaro and Third, Mrs. Miles?"

Connie's eyes went wide with surprise. "I go there because it happens to be along the route I usually follow when taking the daily walks my doctor prescribed. Why?"

"You usually sit for a while beside the rock monument in the center of the park, don't you?"

"I always do. Why do you ask?"

"Why do you choose that spot to sit?"

"For two reasons; because there is a stone bench there to sit on while resting and because I like to feed the chipmunk that has a nest in the monument."

"Get to the point, Whitney." Miles could restrain himself no longer. "Quit beating around the bush-is my wife under suspicion, too?"

"We received an anonymous phone call this afternoon," Whitney said. "It enabled us to intercept a note, although the message meant nothing to us then. It was just a slip of paper in a tin box, and it read: 'Crisscross O.K. No suspicion. Ill on schedule.' "

"What does that have to do with my wife?" Miles demanded.

"After the robot told us of the sabotage, the meaning of the message became clear. It was an absurdly easy message to understand. 'Crisscross O.K. No suspicion' could only mean that the drive controls were still cross-circuited and no one suspected it. As for 'Ill on schedule'-we could only take that to mean that the person guilty of sabotaging the drive controls would pretend to be ill on the day of the ship's take-off-too ill to be in the ship when its drive exploded."

Whitney turned his eyes on Connie again. "As I say, an anonymous phone call tipped us off. This person suggested we look at the monument and we found the message in a crevice inside the monument. That, Mrs. Miles, was only a few minutes after you had left there."

There was a moment of dead silence, then Whitney's voice lashed at Connie like the crack of a whip.

"What do you know about that message?"

June reacted then, and in a manner typical of her. She shoved herself away from the card table with a violence that sent it crashing to the floor and advanced on Whitney with her eyes blazing. "Nothing, you fool!" The words came like the spitting of an infuriated cat. "My sister isn't a spy and she doesn't know anything about that message, you . . .

you-"

Her small hand flashed out to rip her nails down Whitney's face and Knight moved quickly to stop her, catching her wrist, then the other hand as she tried to whirl away from him, bringing her arms down tight against her stomach. She struggled furiously to tear loose, her heart pounding against his arm like that of a small, wild animal.

"June-don't!" Connie was beside them, to lay her hand on June's shoulder. "Quit spitting and fighting, kitten-he's only trying to do his job."

June ceased struggling but the hate still blazed in her eyes. "He called you a spy- n.o.body is going to call my sister a spy!"

"He didn't call me a spy, honey-he just asked me what I know about that message."

"I understand your problem, Whitney," Knight said, releasing June but keeping a wary eye on her, lest she should renew her attack. "Someone is guilty of sabotage and it's your job to find who that person is. But aren't you jumping to conclusions on flimsy evidence?"

"I have no desire to cause anyone embarra.s.sment or discomfort," the cold-eyed Whitney replied. "My business is to sort people into two different cla.s.ses-guilty and innocent. An unexpected question suddenly snapped at a suspect will often go a long way toward indicating the person's guilt or innocence."

"Then why don't you snap some questions at a few others?" June demanded.

"Vickson and the workmen who helped build the ship and George- What makes you so sure-"

"Sit down, June," Connie ordered, going back to her own chair. "Give him a chance to ask his own questions."

June hesitated, half turning away to do as her sister had ordered, then Whitney made the mistake of seconding the order. "Yes, sit down," he commanded, unconsciously rubbing his hand down the cheek that had been her intended target.

She whirled back to face him, the rebellion flaring hotly. "Never mind any such details as dictating our posture-just get on with your questions!" She waited for him to dare repeat his order, standing erect and defiant before him, and an expression of helpless defeat flitted over his face. Knight watched with combined sympathy for him and amus.e.m.e.nt. The cold-eyed Whitney was accustomed to dealing with dangerous men and awing them-but how does a man go about awing a hundred and five pounds of fuming, spitting female wildcat?

"I have no more questions to ask-now," Whitney said. He spoke to Knight. "Dr.

Clarke was in Yuma-we contacted him by phone and he's on his way back, now. He's given orders for public announcement of the postponement of the ship's test flight and when he returns we'll continue the questioning-of everyone connected with the ship, including the robot."

"Have you questioned George at all?" Knight asked.

"Very briefly," Whitney said with a wry smile. "Questioning a robot isn't too informative-a robot does no more than answer each question as it's given. It requires time plus a great many questions to get the entire picture. We questioned the robot briefly, as I say, and learned only that his check showed the drive controls to be cross- circuited. When Dr. Clarke returns, we'll do a thorough job of the questioning."

"Have you questioned Vickson?"

"He was spending the night with friends in Center Junction, we learned. A man was sent after him and they should return any minute."

"Here?"

"We'll all meet at the Computer area gate, then we'll go to Lab Four and find just who is guilty." Whitney turned to Miles. "Since the evidence against your wife is so uncertain, and since she is in frail health, she will remain here. If we need her, we can send a man after her. I'm afraid you'll have to go with me, now. At present, the evidence points only to you. If you're innocent, we'll do everything in our power to prove it. And if you're guilty"-he smiled grimly-"we'll do everything in our power to prove it."

"Thanks," Miles replied with the same grimness. "That's exactly what I want you to do."

Connie got to her feet. "There's no question about his innocence-it's all a ridiculous mistake. But I realize there is no way you can know that until everyone is questioned and the guilty one found. As for the message in the monument-I know nothing whatever about it. I always sit by the monument and feed the chipmunk, but I certainly never knew someone was using it as a place to leave messages for foreign agents."

"This anonymous phone call-doesn't that sound a little fishy?" Knight asked. "Have you traced it?"

"We're trying to," Whitney answered. "We're not at all convinced that Mrs. Miles is guilty of any connection with the affair. With her husband, it's different-he personally installed the circuits and they have been found to have been installed in such a manner as to destroy the ship."

"Couldn't the robot have made a mistake?" Connie asked. "Maybe they aren't cross- circuited at all-maybe the robot just made a mistake in his checking."

"I'm afraid not," Whitney answered. "Your husband will tell you that robots neither make mistakes nor false statements." "That's true, Connie," Miles said, going to her. "But it's also true that I didn't sabotage the drive." He put his arm around her. "I'll be back in a few hours, and everything will be all right."

Whitney moved toward the door, his eyes on Miles. Miles gave Connie's shoulders a quick squeeze and followed Whitney through the door without looking back.

Knight spoke to Whitney as they went through the door. "I'll follow you down in my own car." Whitney said, "All right," then he and Miles went on up the walk. Knight turned back to the two women in the room.

"There's no question about there being a mistake," he said. "What, I don't know. We do know that someone sabotaged the drive controls, but who? We'll rip out the drive- control panel and trace the leads that way-George had to depend upon tracing them with instruments. I'll go down right now-and you'd better go with me, June. Before it's over they'll want everyone who was ever around the ship, and you've been around it almost as much as I have."

June went to the door where Knight waited, then stopped to say to Connie, "Don't you do any worrying about this while we're gone, Connie. We'll be back with Tim's name cleared before noon, you wait and see."

"Of course you will," Connie answered, but it seemed to Knight that she was, for all her composure, suddenly very small and lonely as she stood in the empty room and watched them leave.

The sky was sh.e.l.l-pink in the east, lighting the world with the half-light of dawn, when he backed out of the driveway. June sat silent and thoughtful beside him; worried, despite her a.s.surances to her sister. He drove slowly, trying to fit together the two facts he was convinced were true; Tim Miles had not sabotaged the ship, yet a robot had no incentive to lie.

There were certain characteristics of the robotic brain: A machine is constructed to obey commands; it does not question those commands.

A machine has no volition; it neither acts nor informs unless ordered to do so.

And then he had the answer; so simple that, he felt, a child should have seen it.

A machine would not voluntarily make a false statement, but the prime function of a machine was prompt, unquestioning obedience. The robot, George, would never make a false statement by its own volition, but it would if ordered to do so.

He slowed the car to a barely moving crawl as he considered the implications and June looked at him questioningly. "We're still three blocks from the gate-what's wrong?"

"The drive controls have never been sabotaged. George was ordered to make that statement, and no one thought to ask him if it were true."

"But why? What would anyone gain by getting Tim into trouble like this?"

"It wasn't for personal reasons. Someone didn't want that ship tested today!"

"Then it was-" June stopped as a dull, distant roaring came to them. "It must have been-"

She stopped again as the roaring increased, coming from above them and to the southwest, filling the air like the hum of a billion bees. "What's that?"